The present invention is related to microelectromechanical systems (MEMS) and the fabrication thereof, in general, and more specifically, to a microneedle array module and its fabrication.
Targeted drug delivery or the application of a high concentration of one or more drugs to a specific target area within the body has become of paramount importance to the fight against tumors, restentosis and similar life threatening medical conditions. Generally, these target areas are reachable through the walls of the blood vessels of the body. Present systems use a catheter with an imaging device to locate the target area. Once located, a specific drug or drugs are delivered to the targeted vessel wall area. But, this process has posed serious problems.
One approach provides a drug inside a perforated balloon at the end of the catheter. When the balloon reaches the target area, it is inflated causing the drug to be released through the perforations of the balloon locally around the targeted walls of the vessel. This perfusion of the drug at the surface of the vessel walls relies heavily on the drug being absorbed quickly and efficiently by the vessel walls at the target area. However, in some cases the drug may not be absorbed by the vessel walls very effectively. In these cases, the drug may be caused to move downstream with the blood stream which may cause adverse medical effects to portions of the body not intended to receive the drugs, especially at such high concentrations. The drugs may also be diluted in this delivery process and lose their effectiveness. In any event, these relatively expensive drugs may not be achieving their intended purpose.
Some recent drug delivery systems, like those proposed in the U.S. Pat. Nos. 5,112,305; 5,242,397; 5,681,281; 5,713,863 and 5,746,716, for example, provide for a studded balloon catheter. The balloon or portions thereof contain the drug or drugs to be delivered to the target area. When the balloon reaches the target area, it is inflated causing the studs to press against the vessel walls. The drug is then forced from the balloon through the studs into the surface of the vessel walls. However, the stud protrusions of the balloon are not needles and thus, are not very efficient at puncturing the vessel walls, especially at depths adequate for injecting the specific drug.
What is needed for effective drug delivery is an array of microneedles of sufficient length which may be deployed to the target site within the body and adequately penetrate the vessel walls thereat to permit the drug to effectively act on the target area at the high concentrations intended. Such an array structure may also be used transdermally for drug delivery as well.